Review of Light Design: LED Packaging and Lighting

Prof. Ja-Soon Jang LIFTRC & Yeungnam University

Acknowledgments

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Outline

I.

Introduction of LED Packaging and Lighting

II.

Light Design of LED Packages

III.

Light Design of LED Lightings and Examples

IV.

Conclusions

LED-IT Fusion Technology Research Center(LIFTRC)

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 Development Trend in LED Chip Technology • External Quantum Efficiency(EQE)  • Efficiency Droop  (as the current increases)

Chip Efficiency

• Low Power Consumption

Thin-Film Flip-Chip Flip-chip Thin GaN chip Vertical chip

MESA structure chip

1990

2000

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2005

2010

Year

Nano photonics materials & device Lab

 Development Trend in LED Packaging Technology  Sign/Indicator-based simple bulb packages (~2005)  LED Back Light Unit (BLU) for Display (2005~): SMD types of Top/Side view LEDs  Lighting (2010~) : Ceramic- and metal-based high power LED packages for high-power applicable lightings

Luminous Efficiency (lm/W)

 Smart lighting (2015~) : IT-controllable LED lightings

Cool White (CCT 4,100~6,500K) Warm White (CCT 2,800~3,500K)

Year

LED-IT Fusion Technology Research Center(LIFTRC)

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 Types of Packaged LEDs Package with Substrate or COB

Package with substrate

Types of LED packages

Package power range

Interconnection type to the external interface

Single small size LED

Low power

Through hole

Single medium size LED

Medium power

Surface mount or through hole

Single large size LED

Multiple small size LED

Multiple large size LED

Chip on board (on MC-PCB or ceramic)

Multiple small size LED

Multiple large size LED

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Surface mount

High power

Plug & play connector or solder pads for cable

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 Process steps in LED packaging □ Process

Source : LED Source module technology 2012

Plasma cleaning

Die bonding ▪ Epoxy - Ag epoxy - Silicone - Epoxy ▪ Eutectic bonding - AuSn plating - Solder

Curing

Wire bonding

Curing

▪ Ball bonding ▪ Wedge bonding

Die/ball shear test Wire pull test

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Phosphor coating

Encapsulation

▪ Red, Green, Yellow ▪ Silicon ▪ Coating method ▪ Lens molding - Conventional - Dispensing - Remote - Compression - Conformal - Transfer molding - Vacuum molding

Test ▪ I-V test ▪ Aging test ▪ Optical test

Nano photonics materials & device Lab

 Process steps in LED packaging Source : LED Source module technology 2012

□ Lens molding Dispensing

Part injection is available Merit for Small quantity & various types

Difficulty in obtaining mass-production

Compressive molding

Easy formation of concave & convex lens Liquid Si packing resin is employed Little casting contamination by using hetero-films Co-molding with phosphor and Si resin

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Transfer molding

Vacuum molding

Higher molding capability Short processing time without hetero-films Mass-production available Molding of lead-frame types Removal of bubble is easy may be available Difficulty in using liquid Si packing resin

Nano photonics materials & device Lab

 Key Issues of Packaged LEDs

Source : LED Source module technology 2012

Source : L&D Korea 2011

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Rapid Expansion of LED Lighting Markets

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Outline

I.

Introduction of LED Packaging and Lighting

II.

Light Design of LED Packages

III.

Light Design of LED Lightings and Examples

IV.

Conclusions

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Key Issues in Light Design of LED Packages  Key issues of phosphor-coated LEDs Correlated Color Temperature (CCT) and Color Rendering Index (CRI) Angular uniformity of color distribution Higher conversion efficiency (Blue/UV  Phosphors) Good reliability

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 CRI CRI: the ability to show (or render) the true colors of physical objects that are being illuminated by the light sources Examples:

LED-IT Fusion Technology Research Center(LIFTRC)

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 CT and CCT •

•

The color temperature (CT) of a white light source is the temperature of a Planckian blackbody radiator that has the same chromaticity location as the white light source is considered. The correlated color temperature (CCT) of a white light source is defined as the temperature of Planckian black-body radiator whose color is closet to the color of the white light source.

Lines of constant correlated color temperature in the (x, y) chromaticity diagram. Whereas the correlated color temperature follows from the minimum distance to the planckian in the (u’, v') diagram, this is not the case in the (x, y) diagram (after Duggal, 2005).

LED-IT Fusion Technology Research Center(LIFTRC)

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 Color coordinates: Bin

Source : Proc. SPIE vol. 6486

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Factors of color Uniformity Phosphor particle

Encapsulation resin (epoxy or silicon)

Converted light

Blue chip light

chip Die paste

Most common factors influencing color coordinate deviations of conversion LEDs Volume of phosphor contributing to light conversion → concentration → casting height Chip wavelength ƛ Chip position deviations

Silver plated Metal lead-frame

- Package types - Package size - Lens structure - Phosphor thickness - Density (Uniformity) - Chip position

Source : LED Source module technology 2012

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Types of phosphor coating • The spatial phosphor distribution in white LED lamps strongly influences the color uniformity and efficiency of the lamp • (i) Proximate phosphor distribution by Nichia in 1990s - The phosphor particles are dissolved in the encapsulation material that is dispensed into the reflector cup - Gravity, buoyancy, and friction generally lead to a distribution of phosphor particles • (ii) Conformal phosphor distribution - accomplished by wafer-level phosphor dispensation thereby lowering the cost - provides a small-emission area and high luminance because a point-like source is desirable for imaging-optic applications like automotive headlights • (iii) Remote phosphor distribution - the phosphor is spatially distanced from the semiconductor chip - the phosphorescence impinges on semiconductor chip is greatly diminished if d > a

LED-IT Fusion Technology Research Center(LIFTRC)

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 Phosphor coating dependence on angular uniformity Dotting

Proximate

remote

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 Conformal Coating Methods  Conformal Coating by Squeezing

 Conformal Coating by Spin-coating

Comparison of radiation distribution between dispensing and conformal coating 0 -15

100

-30

80

15

30

-45

60

45 60

-60

40 75

-75 20 0 20 40

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-90

90

LG WOOREE ETI Conformal coated LED

Nano photonics materials & device Lab

 (Phosphor + Resin) combination-ratio influence on CCT and CRI Mix ratio

Temp

Time

87:13

32 ℃

400 ms

88:12

32 ℃

400 ms

89:11

32 ℃

400 ms

Mix ratio

mW

CIE

CCT

CRI

87:13

287.1991~311.1051

X=0.3404, Y=0.3609 X=0.3466, Y=0.3742

5092.0794~5160.5173

65.0452~66.2312

88:12

290.4969~316.139

X=0.3281, Y=0.3426 X=0.3341, Y=0.3533

5436.7839~5690.0927

67.4859~68.8287

89:11

292.1195~302.4635

X=0.3212, Y=0.3297 X=0.3256, Y=0.3357

5817.6044~6050.6478

69.0395~70.6549

Mix ratio

Temp

Time

88:12

32 ℃

350 ms

88:12

32 ℃

400 ms

88:12

32 ℃

450 ms

Mix ratio

mW

CIE

CCT

CRI

88:12 (350 ms)

333.8458.~346.6808

X=0.3249, Y=0.3365 X=0.3289, Y=0.3428

5655.121~5848.943

67.5906~70.3587

88:12 (400 ms)

328.0.549~346.5998

X=0.3281, Y=0.3426 X=0.3341, Y=0.3533

5436.7839~5690.0927

67.4859~68.8287

88:12 (450 ms)

327.9409~346.9457

X=0.3442, Y=0.3673 X=0.3491, Y=0.3794

4951.2980~5081.4090

64.2635~65.1898

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Phosphor & Lens in LED packages: Geometry-dependence on LEE

Light propagation in the cup of different tilted angles: a) 0 degree; b) 37 degree; c) 55 degree. OPTICS EXPRESS, Vol. 18 (2), 2010

LED-IT Fusion Technology Research Center(LIFTRC)

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 Lens Design of LED packages The illuminance of the point (x,y) is generated by 4 LEDs in 2 × 2 array. Point (0,0) corresponds to the central point of the region enclosed by the 4 LEDs. Parameters to calculate the illuminance generated by the ith (i = 1~4) LED are indicated in the figure

Illuminance distributions in the direction of x axis of the gray region where (a)dz1 = 28.90mm, (b) dz2 = 37.90mm, (c) dz3 = 65.12mm, (d) dz4 = 83.78mm

Optics Express 18(16), 17460 (2010)

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Geometry dependence of lens

Lighting performance of (a) a traditional LED packaging and (b) the ASLP. ASLP had advantages of much smaller size in volume (~1/8), higher system lumen efficiency (~8.1%), lower cost and more convenience for customers to design and assembly Effects of installation errors on lighting performance of the application specific LED packaging (ASLP): (a) horizontal deviation dH; (b) vertical deviation dV and (c) rotational deviation θR 2009 International Conference on Electronic Packaging Technology & High Density Packaging (ICEPT-HDP)

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Outline

I.

Introduction of LED Packaging and Lighting

II.

Light Design of LED Packages

III.

Light Design of LED Lightings and Examples

IV.

Conclusions

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Configuration of LED Lightings Source : Lucenat

Reflector system

Lens

LED package

Heat sink LED driving module

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Light Design Concept of LED Lightings □ Design of LED lighting Lamp Electrical

Harmony

Design Interpretation

Convergence Design Efficient

Physical

Functionality

Optical

Design Approach

Design Pattern Structure

- Creation of various Light source color and application of sensitivity Lighting. - Simple control - Small size and simple driver circuit → Possible miniaturization and lightweight design

LED-IT Fusion Technology Research Center(LIFTRC)

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 Light Design Factors • Well defined optic design that is suitable for lighting applications - illumination uniformity on effective lighting-area Design of second optic lens - illumination angle and selective lighting is necessary - Appropriate radiation patterns from LED module

Illumination patterns on the street for a (a) spherical and (b) cylindrical lens

The schematic diagram of on-board LED array fish-attractors.

Optics Express 21(3), 3201 (2013)

LED-IT Fusion Technology Research Center(LIFTRC)

Optics Express 20(24), 26135 (2012)

Nano photonics materials & device Lab

 Design of secondary lens for street lightings

Optics Express 21(3), 3201 (2013)

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Design of secondary lens for street lightings

Optics Express 21(3), 3201 (2013)

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Design of secondary lens for street lightings

The illumination pattern of the spherical lens produced a Lambertian distribution, while the cylindrical lens produced a bat-wing distribution. In the design of a cylindrical lens, the illumination could extend to 70 degrees and 30 degrees in the x and y directions separately, but there was uniform illumination for the rectangular distribution.

LED-IT Fusion Technology Research Center(LIFTRC)

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 Design of radiation patterns for fishery lightings Simulation results MH Lamp

LED-1 Lamp similar with MH Lamp

Flat-type LED Lamp

Set-up conditions for MH Lamp (80 ea) and LED Lamp (120 ea)

LED-IT Fusion Technology Research Center(LIFTRC)

Ref: 한국조명설비학회지 2012

Nano photonics materials & device Lab

 Light Design for various lighting applications Dental-surgical Lighting Design

• Key factors

 High power, CCT, Controllable illumination patterns

Optic Design

Heat Dissipation Design

Power

illumination

Pattern size

CRI(Ra)

CRI(R9)

CCT

Target

100W

> 50,000㏓

R=14㎝~25 ㎝

80 ↑

80 ↑

3,800~4,800K

Results

100W

50,000㏓

20㎝

84

81

4,500K

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Light Design for various lighting applications Dental-care Lighting Design

LUVIS

LED Lighting (LUVIS)

General Lighting

Halogen Lighting

Comparison of illumination patterns of LED dental care lighting and halogen lighting Power

illumination

Pattern size

Target

10W

> 15,000㏓

14㎝×7㎝

90 ↑

90 ↑

5,000~6,000K

Results

9W

(Max.) 17,000 ㏓

13㎝×7㎝

95

90

5,500K

LED-IT Fusion Technology Research Center(LIFTRC)

CRI(Ra) CRI(R9)

CCT

Nano photonics materials & device Lab

 Light Design for various lighting applications • Candle Lightings Feature

Sample image

light distribution Polar Distribution

Luminance Limiting Curve

ISO Lux Diagram

Grayed Illuminance

Narrow Top

Filament

Narrow Top + Spherical Bulb

Narrow Top + aspherical Bulb

LED-IT Fusion Technology Research Center(LIFTRC)

Nano photonics materials & device Lab

 Light Design for various lighting applications • Optic Design of LED Down-light (DIALux)

• LED street Lighting (CATIA)

 Vertical illuminance and radiation distribution are optimized LED Array Pitch 8㎜×8㎜

100㎜ Light source modeling 195㎜

Light-system modeling

• Model : Philips Fortimo LED HBMt • Input photons : 6,000㏐×4EA,

Input power : 54W

• Total Input lm : 24,000㏐ • Total Output lm : 16,926㏐ • Maximum luminous

Measurement distance: 4m, 262.4㏓

intensity : 6,669㏅ • Peak Angle : 58.6º • Light efficiency : 70.5% (=Output lm/Input im)

Measurement distance: 5m, 166.0㏓ Illumination patterns

Simulation for radiation patterns Radiation patterns

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Thank you very much!

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